The invention relates to a magnetic tape cassette for a recording and/or reproducing apparatus (hereinafter referred to as a tape recorder); containing a magnetic tape which is disposed substantially between two housing halves of the cassette, which cassette in order to prevent inadvertent erasure of a prerecorded magnetic tape is provided with at least one erase interlock device which comprises an actuating member movable over a defined path in the cassette to at least two normal operating positions which alternatively close or unblock an opening formed in one of the housing halves. Such a cassette is placed on an apparatus which is provided with a sensor, interlocked with a recording control, which sensor senses the opening and is movable between a first position corresponding to a first operating position of the actuating member, in which position the recording control may be switched to its recording position and a second position corresponding to a second operating position of the actuating member, in which position the recording control is locked in its inactive position.
In a known cassette of this type, as is for example described in German Offenlegungsschrift 2,604,172, the actuating member of the erase interlock device is simply movable between two operating positions, the erase interlock being operative in one of the two operating positions and inoperative in the other position. When designing an erase-interlock device care must be taken that its actuating member cannot inadvertently be set to that operating position in which a recording control can be switched to the recording mode, so as to prevent inadvertent erasure of a prerecorded tape. Therefore, as is known from German Offenlegungsschrift No. 2,616,895, it has been proposed to provide the actuating member of an erase-interlock device with a latching device which can only be released deliberately, so as to prevent accidental disabling of the erase interlock device. This increases the reliability with which such an erase interlock device operates, but it also complicates the operation of said device, which is not an advantage in situations where it is desirable that the erase interlock device can be actuated simple and quickly.